Working on Your Delts. The deltoid muscle is the main muscle that allows you to raise your arm or hold it out. It is connected to the humerus of the upper arm. The person shown below is holding his arm out horizontally with a $2\mathrm{.}50$ kg weight in his hand. The weight is $60\mathrm{.}0$ cm from the shoulder joint. His forearm $($including his hand$)$ has a mass of $2\mathrm{.}44$ kg and is $34\mathrm{.}0$ cm long; its centre of mass is $43\mathrm{.}0$ cm from the shoulder joint, measured along the arm. His upper arm is $26\mathrm{.}0$ cm long and has a mass of $2\mathrm{.}63$ kg; its centre of mass is $13\mathrm{.}0$ cm from the shoulder joint. The deltoid muscle is attached to the humerus $15\mathrm{.}0$ cm from the shoulder joint and makes an angle of $14\mathrm{.}0($degrees$)$

with the humerus.

a$)$ Make a free body diagram of the arm. Recall that the location of each force is important, and make sure to also include the reaction force at the pivot. $(4)$

b$)$ What is the tension in the deltoid muscle in the case described above? $(4)$

c$)$ What is the magnitude of the strain force in the shoulder joint?